So, spring arrived on 1st March – well, meteorological spring did. Consequently it snowed in many parts of the UK. The ever reliable British weather is throwing us some more curveballs, with near freezing temperatures and high winds, followed by a few days of ‘unseasonably warm’ bright sunshine and warm spells. The poor old daffodils won’t know whether to bloom or stay in the ground a week or two longer.
So, given the changeable and wintry conditions – why is it “officially” spring already up here in the northern hemisphere? Well, it is and it isn’t, so we thought it might be helpful to explain the difference between meteorological and astronomical springs…
Spring – the part of the year when we get all excited. The sun is showing his face a little more, the daylight hours are noticeably longer and it won’t be long before it’s time to barbecue again. Soon you’ll have to think about getting the garden furniture out of winter storage and back to the patio.
But hang on. It’s only spring if you subscribe to the meteorological definition. If you’re more of an astronomy kind of soul then you’ve got another 2 weeks to wait. The 20th March to be exact. Which is when the spring equinox will occur in 2015. But why are there two definitions and how do they differ? Here goes…
Meteorology is all about making observations, spotting patterns and then forecasting – based on what you have learned. To make life easy, meteorologists divided the seasons into the 1 months of the gregorian calendar. Summer includes June, July and August, Autumn is September October and November, Winter December, January and February and Spring – beginning in March, includes April and May.
Defining the seasons in this manner means the boffins can compare the weather from each year to the next. It’s one of the key ways of measuring, resulting in the phrase ‘The hottest/driest/wettest/coldest since records began”. Handy then whether you’re a geography teacher, seasoned climatologist, or just the average Brit who likes to talk about the weather.
That’s astronomical, not astrological – the important bit being this is about the physics of the Earth’s orbit round the sun, not the month’s horoscope informing you that you’re about to strike it rich, find love or face a rocky week at work. We explained in December how the Earth’s elliptical orbit round the sun makes for longer days, shorter nights (and vice versa).
The Spring and Autumn Equinox’s are the halfway point between the summer and winter solstices – when daylight hours are equal to night time hours. Effectively it’s when the planet is halfway along the long parabolic curve it travels whilst orbiting the sun.
We’ll leave it to you to choose which spring you’re going to put your faith in, but we’ll be back on 20th March with part 2 – exploring the spring equinox. Hopefully, by then things will have warmed up a bit and the sun will be out.